Preventive measures and temperature control for explosion of trolley annealing furnace

1, Cause analysis and prevention measures of explosion:
1. Reason for explosion of trolley annealing furnace:
(1) Overpressure: The stress of the pressure component exceeds the strength limit and fractures.
(2) Over temperature: The material of the pressure element exceeds its allowable operating temperature, causing cracking due to decreased strength or severe water shortage.
(3) Wear and corrosion: Wear thins materials and reduces their pressure bearing capacity; Corrosion causes the steel plate to undergo corrosive embrittlement.
(4) Cracks: Frequent starting and stopping of annealing furnaces or frequent fluctuations in pressure and load, leading to fatigue cracks.
The main reasons are congenital defects (problems with the annealing furnace itself) and poor operation management (incomplete safety accessories, failure, illegal operation and unauthorized departure, inadequate equipment operation, failure to detect hidden dangers such as cracks and corrosion in a timely manner, water treatment facilities or water treatment facility failures, etc.).
2. Preventive measures for annealing furnace explosion:
(1) Prevent overpressure (regularly perform manual and automatic discharge to prevent rusting of safety valves; regularly flush the drain under the pressure gauge; regularly conduct water pressure tests on equipment that has been out of service for a long time).
(2) Prevent overheating (water shortage and scaling).
(3) Prevent corrosion (maintain water treatment standards, ensure water supply and boiler water quality, strengthen shutdown maintenance, and promptly clean smoke and dust).
(4) Prevent cracking and slotting (stable combustion, quenching and heating are prohibited).
(5) Strictly prohibit early defects (strictly control the acceptance of new annealing furnaces and repaired annealing furnaces).
2, Temperature control during annealing process:
The trolley annealing furnace adopts dual closed-loop control of combustion chamber temperature and loading chamber temperature. The temperature setting for closed-loop control of combustion chamber temperature is 850 ℃ higher than the temperature of the heating hood. Switch between two closed loops based on the current temperature rise of the heating hood and the temperature of the material chamber. The specific switching conditions are as follows:
(1) If the combustion chamber temperature is greater than or equal to its set value, it is necessary to switch from the combustion chamber closed-loop to the combustion chamber closed-loop.
(2) If the actual temperature of the combustion chamber increases by 10 ℃, or exceeds the set value of the heating hood, or the actual temperature of the loading chamber decreases by 15 ℃, the closed-loop control of the combustion chamber should be switched back.
The control methods are divided into adjustment control and switch control. The specific conversion conditions are:
(1) When the trolley annealing furnace has the following situations, it must switch from regulating control to on/off control: the combustion chamber temperature is 10 ℃ or higher than the set value, and the electric valve has reached the lower limit of the set value; Or if the temperature in the material room is 4 ℃ or higher than the set value, the electric valve has reached a lower set value; Or the temperature in the material room is higher than the set value by 7 ℃ or even higher.
(2) Switch from switch control to adjustment control in the following situations: the combustion chamber temperature drops to 15 ℃ or below the set value; Or the temperature in the material room drops to 6 ℃ or below the set value. In the temperature regulation control of the trolley annealing furnace, a P regulator is used and cascade control is adopted. The temperature closed-loop control is the main circuit, the actuator is air flow regulation, the gas flow control is a secondary circuit, and the actuator is a gas flow regulation valve.